Abstract

Embedded 3D Printing of Dilute Particle Suspensions into Dense Complex Cardiac Fibers

Jeroen Rouwkema, Associate Professor, University of Twente

In order to fabricate functional organoids and microtissues, a high cell density is generally required. As such, the placement of cell suspensions in molds or microwells to allow for cell concentration by sedimentation, is a standard method for the production of organoids and microtissues. Even though molds offer some level of control over the shape of the resulting microtissue, this control is limited as microtissues tend to compact towards a sphere after sedimentation of the cells. 3D bioprinting offers better control over the shape of the resulting structure. However, when using extrusion 3D bioprinting, the self-assembly into organoids can be hampered due to low cell densities or the presence of bio-ink components which interfere with the self-assembly process. Even though the printing of dense cell suspensions without the addition of a biomaterial component in the ink has been reported, extruding dense cellular suspensions is challenging due to potential clogging of the printing nozzle and the exposure of the cells to high shear stresses. To circumvent these limitations, we have developed  a simple and inexpensive embedded printing method to 3D print dense functional tissues using dilute (volume fraction < 10%) aqueous particle suspensions as an ink. These particles can be cells, spheroids, hydrogel beads, or combinations thereof. Using this approach, we have shown the formation of large functional and beating cardiac tissue fibers using human pluripotent stem cells.